Nanoparticle clusters formed from individual nanoparticles of two or more types

Abstract

Nanoparticle clusters are described. In particular nanoparticle clusters formed from two or more individual nanoparticles of different types are described and methods for fabricating such nanoparticle clusters are further described. These nanoparticle clusters are fabricated by surface activating individual ones of the plurality of nanoparticles by desorption of surfactant molecules from the surface of the coated nanoparticles through exposure of the individual ones of the plurality of nanoparticles to an activating agent.

The invention claimed is: 
     
       1. A method of forming nanoparticle clusters of nanoparticles of at least a first and a second type, the method comprising:
 a. providing in a first step, a plurality of individually coated nanoparticles of a first type in suspension, the nanoparticles being coated with a plurality of surfactant molecules; 
 b. providing in a second step, a plurality of nanoparticles of a second type into the suspension of nanoparticles of the first type, the second type being different from the first type; 
 c. surface activating individual ones of the plurality of nanoparticles of the first type by desorption of surfactant molecules from the surface of the coated nanoparticles through exposure of individual ones of the plurality of nanoparticles of the first type to an activating agent; 
 d. allowing, through the expiration of time, activated nanoparticles to combine to form clusters of nanoparticles through a physical interaction, and 
 e. terminating the formation of nanoparticle clusters by one of bringing the plurality of nanoparticles of the second type into contact with the nanoparticles of the first type, or removing the suspension from contact with the activating agent, or introducing nanoparticles of a third type into the suspension, and 
 wherein the formed nanoparticle clusters comprise nanocomposites with identifiable individual nanoparticles of the first type, individual nanoparticles of the second type and surfactant molecules. 
 
     
     
       2. The method of  claim 1 , wherein the dimensions of the formed clusters are determined by the timing of the bringing the plurality of nanoparticles of the second type into contact with the nanoparticles of the first type. 
     
     
       3. The method of  claim 1  wherein the plurality of nanoparticles of the second type are brought into contact with the nanoparticles of the first type prior to the growth of clusters of nanoparticles of the first type. 
     
     
       4. The method of  claim 1  wherein the plurality of nanoparticles of the second type are brought into contact with the nanoparticles of the first type after the growth of clusters of nanoparticles of the first type. 
     
     
       5. The method of  claim 1  wherein the dimensions of the formed clusters are determined by the timing of removal of the suspension of nanoparticles of the first type from contact with the activating agent. 
     
     
       6. The method of  claim 1  wherein the growth of the nanoparticle clusters within the suspension is monitored to determine an appropriate time for termination of said growth. 
     
     
       7. The method of  claim 6  wherein the monitoring is a continuous process or is effected over a plurality of iterations. 
     
     
       8. The method of  claim 1  wherein the termination of formation of the nanoparticle clusters is effected after expiration of a predefined time period. 
     
     
       9. The method of  claim 1  wherein the activating agent is a substrate. 
     
     
       10. The method of  claim 9  wherein the substrate is a silica substrate. 
     
     
       11. The method of  claim 10  wherein the silica substrate is formed from grafted silica. 
     
     
       12. The method of  claim 1  provided in a flow through arrangement whereby dialysis across a membrane affects a reduction in the concentration of a stabilised suspension resulting in generation of activated nanoparticles and growth of nanoparticle clusters. 
     
     
       13. The method of  claim 1  wherein the suspension is provided in a flow through arrangement. 
     
     
       14. The method of  claim 1  wherein the suspension includes magnetic nanoparticles. 
     
     
       15. The method of  claim 1  wherein the suspension includes fatty-acid coated nanoparticles. 
     
     
       16. The method of  claim 15  wherein the nanoparticles of the first type are iron-oxide nanoparticles. 
     
     
       17. The method of  claim 1  wherein the nanoparticles of the first and second type are coated with surfactant molecules, the surfactant molecules coating the nanoparticles of the first type differing from those coating the second type. 
     
     
       18. The method of  claim 17  wherein the nanoparticles forming the nanoparticles of the first type are the same as the nanoparticles forming the nanoparticles of the second type, the surfactant coating applied to each of the first and second types being different. 
     
     
       19. The method of  claim 1  wherein the surfactant comprises at least one of oleic acid or GLYMO. 
     
     
       20. The method of  claim 1  comprising re-activating a previously stabilised nanoparticle cluster to prepare size-controlled nanostructures with a radially variable or multi-layered composition. 
     
     
       21. The method of  claim 1  including stabilizing the nanoparticle clusters and wherein the stabilizing provides for:
 a) a cross-linking and phase transfer of the nanoparticle clusters into a stable aqueous solution, or 
 b) an embedding of the clusters in a polymer matrix, or 
 c) encapsulating the clusters with suitable amphiphilic molecules, such as a lipids. 
 
     
     
       22. The method of  claim 1  wherein the nanoparticles of the second type are bio-molecules. 
     
     
       23. The method of  claim 1  wherein the terminating the formation of nanoparticle clusters comprises introducing nanoparticles of a third type into the suspension, the nanoparticles of the third type being bio-molecules. 
     
     
       24. A method of forming nanoparticle clusters comprising:
 a. providing oleate stabilised magnetic nanoparticles of a first type in a suspension, 
 b. effecting a desorptive loss from the surface of the nanoparticle of a previously temporarily adsorbed oleate molecule on the nanoparticle's surface so as to form a surface activated reactive nanoparticle through exposure to an external activating agent, 
 c. stabilising the surface activated reactive nanoparticle through physical interaction and combination with other reactive nanoparticles and the provision of a plurality of nanoparticles of a second type into the suspension, the second type being different from the first type, the stabilisation resulting in the formation of clusters comprising nanocomposites with identifiable individual nanoparticles of the first and second type. 
 
     
     
       25. The method of  claim 24  wherein the surface activated nanoparticles are activated through interaction with a substrate. 
     
     
       26. The method of  claim 25  wherein the interaction is through an adsorption process whereby capping molecules from the nanoparticles are adsorbed onto the surface of the substrate. 
     
     
       27. A method of using nanoparticle clusters in a biomedical application, the method including:
 a. forming one or more nanoparticle clusters in accordance with the method of  claim 1 , 
 b. introducing the formed nanoparticle clusters into the body. 
 
     
     
       28. A method of forming a drug delivery agent, the method including of:
 a. forming one or more nanoparticle clusters in accordance with the method of  claim 1 , and 
 b. encapsulating the one or more nanoparticle clusters within a heat sensitive medium, the heat sensitive medium providing a carrier for a predefined pharmaceutical compositions. 
 
     
     
       29. A method of delivering a pharmaceutical composition within a body, the method including the formation of a drug delivery agent as claimed in  claim 28 , introducing the agent to a body and then causing a generation of heat within the agent through stimulation of the one or more nanoparticle clusters for therapeutic purposes or to effect disruption of the agent and the release of pharmaceutical composition. 
     
     
       30. The method of  claim 29  wherein the stimulation of the nanoparticle clusters is achieved through at least one of:
 a. applying a static magnetic field to the area where the agent is located, 
 b. applying an RF field to the area where the agent is located, 
 c. using a laser to target the area where the agent is located. 
 
     
     
       31. The method of  claim 30  wherein the static field provides for a localisation of the nanoparticle clusters at a defined location. 
     
     
       32. The method of  claim 31  wherein the RF field provides for a heating of the nanoparticle clusters. 
     
     
       33. The method of  claim 31  wherein the laser provides for a heating of the nanoparticle clusters. 
     
     
       34. A method of forming a contrast agent comprising magnetic nanoparticle clusters comprising the method of  claim 1 . 
     
     
       35. A method of forming a mediator for assisting in hyperthermia treatments comprising the method of  claim 1 . 
     
     
       36. A method of forming a catalyst, the catalyst having one or more nanoparticle clusters formed on a surface of a substrate, the method including:
 a. providing one or more nanoparticle clusters in accordance with the method of  claim 1 , 
 b. applying the formed nanoparticle clusters onto the surface of a substrate, and 
 c. annealing the applied nanoparticle clusters to provide for a thermal desorption of adsorbed species from the applied nanoparticle clusters. 
 
     
     
       37. A method of forming clusters of nanoparticles, the formed clusters having individual and distinct nanoparticles of at least a first and a second type, the method comprising:
 a. providing a plurality of nanoparticles of a first and of a second type in a suspension, the first type being different from the second type, the individual nanoparticles of at least one of the nanoparticles of the first or second type being stabilised through provision of a plurality of surfactant molecules on their surface; 
 b. effecting a desorption of the surfactant molecules from the surface of the nanoparticles to surface activate individual ones of the plurality of nanoparticles, the desorption being effected through exposure of individual ones of the plurality of nanoparticles to a physical activating agent; 
 c. allowing, through the expiration of time, activated nanoparticles to combine to form clusters of nanoparticles; and 
 d. stabilising the formed nanoparticle clusters, the formed nanoparticle clusters comprising nanocomposites with identifiable individual nanoparticles of the first type, individual nanoparticles of the second type and surfactant molecules.